Show/Hide shipping methods based on order weight

functions.php

add_filter( 'woocommerce_package_rates', 'show_shipping_method_on_order_weight', 10, 2 );

function show_shipping_method_on_order_weight( $available_shipping_methods, $package ) {
	
	$order_weight = 0;
	foreach( WC()->cart->cart_contents as $key => $values ) { 
		$product_weight	= woocommerce_get_weight($values[ 'data' ]->get_weight(),'lbs');
		$quantity 		= $values['quantity'];
		if($product_weight && $quantity){
			$order_weight = $order_weight + $product_weight*$quantity;
		}
	}
	$weight_oz = $order_weight*16;
	if($weight_oz <= 6){
		$shipping_services_to_hide	=	array(
			'wf_shipping_usps:flat_rate_box_priority',
			'wf_shipping_usps:flat_rate_box_express',
			'wf_shipping_usps:D_FIRST_CLASS',
			'wf_shipping_usps:D_EXPRESS_MAIL',
			'wf_shipping_usps:D_STANDARD_POST',
			'wf_shipping_usps:D_MEDIA_MAIL',
			'wf_shipping_usps:D_LIBRARY_MAIL',
			'wf_shipping_usps:D_PRIORITY_MAIL',
			'wf_shipping_usps:I_EXPRESS_MAIL',
			'wf_shipping_usps:I_PRIORITY_MAIL',
			'wf_shipping_usps:I_GLOBAL_EXPRESS',
			'wf_shipping_usps:I_FIRST_CLASS',
			'wf_shipping_usps:I_POSTCARDS',			
		);
	}else{
		$shipping_services_to_hide	=	array('flat_rate');
	}
	
	foreach ( $shipping_services_to_hide as &$value ) {
		unset( $available_shipping_methods[$value] );		
	}
	return $available_shipping_methods;
}